In the manufacture of sweetened ready-to-eat cereals, sweet coatings are commonly applied to a cereal base material, especially coatings containing the sugar sucrose.
Although sucrose has excellent organoleptic properties in cereal coating applications, it is well known that the large amounts of sucrose consumed in the typical American's diet contributes to obesity and dental caries. A recognition of this fact among consumers has led to intensive efforts in the food industry to find sweeteners to replace sucrose in many food products. One of the most successful approaches has been to replace sucrose with dipeptide sweeteners, especially sweeteners based on the amino acid L-aspartic acid. The most commercially successful of this group has been L-aspartyl-L-phenylalanine methyl ester, also known as aspartame, a sweetener approximately 200 times as sweet as sucrose and which has similar sweetness characteristics.
Incorporation of dipeptide sweeteners in food coatings is not, however, a matter of simple replacement of sucrose. Characteristic differences between dipeptide sweetners and sucrose include reduced bulk due to its high sweetening power, instability of the sweetener molecule when incorporated in many foods and its high cost. In particular, aspartame is known to be unstable in the presence of moisture; hydrolysis of the dipeptide bond, hydrolysis of the methyl ester group and/or cyclization to diketopiperazine can occur, all which destroy the sweetness of the aspartame molecule. Further, since aspartame is an aspartic acid based dipeptide, it has a free amine group available for browning reactions with the reducing sugars present in many foods; reactions which can reduce the sweetness and change the flavor of the food product during processing and storage.
Many known methods for coating a ready-to-eat cereal with dipeptide sweeteners apply a dipeptide sweetener such as aspartame to the ready-to-eat cereals in an aqueous solution together with bulking and texture improving agents such as dextrins or vegetable protein. These coating methods have a number of disadvantages. First, during processing and long term storage of comestibles coated with aspartame, contact of the free amine group of aspartame with reducing groups present in any dextrins or reducing sugars in the ready-to-eat cereal can cause a browning reaction which reduces the sweetness of the product, causes the formation of brown reaction products on the product surface and causes the formation of the typical flavor elements of browning reactions. Second, since a slight delay in sweetness may be detected in aspartame sweetened products by some persons, incorporating aspartame in a dextrin or vegetable protein coating may further reduce or delay the sweetness impact of aspartame. Third, due to the instability of aspartame in water, applying aspartame to the ready-to-eat cereal in aqueous solution or suspension may cause substantial degradation of aspartame during the application and drying process.
It is therefore an object of the present invention to provide a method for making a sweet, coated ready-to-eat cereal in which the dipeptide sweetener is stable during applition.
It is also an object of the present invention to provide a sweet, coated ready-to-eat cereal in which the dipeptide sweetener remains stable when in contact with a ready-to-eat cereal base containing reducing sugars.
It is also an object of the present invention to provide a sweet, coated ready-to-eat cereal with a strong sweetness impact.